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How the concentration of brine affects the conduction of electricity.

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Electrolysis Investigation Aim: How the concentration of brine affects the conduction of electricity Background Information: Electrolysis: Metals that are more reactive than carbon are extracted by electrolysis. Electrolysis is the break down of a substance by electricity. Electrolysis only occurs in when an ionic substance is molten or is in solution. A substance that can be electrolysed is called an electrolyte. Electrolytes are made up of ions. Electrolytes need to be molten or in solution, so that the ions present are free to move. Ionic compounds have high melting points, so it is often easier to electrolyse the solution of the ionic compound. When the electrodes are connected to a source of direct current one, called the cathode, becomes negatively (-) charged while the other, called the anode, becomes positively (+) charged. The positive ions in the electrolyte will move toward the cathode and the negatively charged ions toward the anode. This migration of ions through the electrolyte constitutes the electric current in that part of the circuit. The migration of electrons into the anode, through the wiring and an electric generator, and then back to the cathode constitutes the current in the external circuit. ...read more.


I will do it carefully; taking special care and attention when I am using the electrical equipment. The electrodes will be 'live', and the electrolyte will only have a current being passed through it for a short amount of time. I will also take care due to the chlorine and hydrogen gases being produced when the current is passing through the circuit. Prediction: I believe that in this experiment, the higher the concentration of the sodium chloride solution, the greater conduction of electricity. When brine is electrolysed, sodium is produced at the cathode and chlorine at the anode. Sodium particles in the solution have been attracted to the negative cathode, so they are positively charged. At the same time, chlorine is produced at the positive anode, so the chlorine particles in the same electrolyte must be negatively charged. The flow of electricity is from the anode (+) to the cathode (-). So in this experiment I should see that the more electrons that are given up and taken at the anode and cathode (more salt) the greater flow of electrons must mean that the conduction of electricity is increased. ...read more.


Current reading from salt solution in Ampere. 4 0.52 8 0.95 12 1.18 16 1.20 20 1.21 Evaluation: The method I used for my investigation was suitable for the aim given and a reliable method. I know this because both my results were very similar. Furthermore, there were no anomalous results. I could have made the results even more accurate by instead of just using 4g of salt I could have worked out what 1 molar of the salt for the solution would be. This would have made my results more reliable as it would be a very precise procedure. These results are enough to support a firm conclusion that increasing the concentration of the salt solution causes greater conduction of electricity. If I were to do this investigation again I would use the molarity method previously stated, would do a preliminary investigation to see if other factors may account for am increase of decrease in the conductivity of a circuit. i.e. if temperature of the water used does anything to the salt. I would also clean the electrodes because debris from other experiments could still be on the surface, which could produce other substances. ?? ?? ?? ?? ...read more.

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Here's what a star student thought of this essay

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Response to the question

The focus of the question is done well. The question shows good underlying research and predictions throughout the experiment. To improve, they should consider further improvements that could be done to make the experiment more reliable.

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Response to the question

The focus of the question is done well. The question shows good underlying research and predictions throughout the experiment. To improve, they should consider further improvements that could be done to make the experiment more reliable.

Level of analysis

The candidate explains the background of the experiment very well, and explains how concentration may affect the experiment in simple and concise terms. The candidate does not explain what brine is from the start which would be good so their understanding of what brine is becomes clear. It would be more correct to use the term NaCl. The candidate should expand on why they are keeping certain factors constant in the fair test section to show their understanding on how different factors may affect the results. Their prediction is good and takes into account the background researched. They provide viable ways to improve the experiment in their conclusion. Decimal places are kept consistent which is good.

Quality of writing

The apparatus list layout looks slightly messy, it should be tidier and presented in bullet points. The diagram does not appear in the PDF. Punctuation, spelling and grammar are all to a good level.

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Reviewed by skatealexia 23/08/2012

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